CN108358221B - Process for preparing lithium chloride from magnesium sulfate subtype salt lake brine - Google Patents
Process for preparing lithium chloride from magnesium sulfate subtype salt lake brine Download PDFInfo
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- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/04—Halides
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
A process for preparing lithium chloride from magnesium sulfate subtype salt lake brine comprises the following steps: (1) freezing nitre in magnesium sulfate subtype salt lake brine at low temperature to obtain purified raw water; (2) nano-filtering and separating the purified raw water to obtain lithium-rich produced water and nano-filtered concentrated water; (3) evaporating to obtain high-concentration lithium-containing mother liquor; (4) adding low-carbon alcohol into high-concentration lithium-containing mother liquor, dissolving out crystals, and carrying out solid-liquid separation to obtain a lithium chloride feed liquid; (5) and recovering low-carbon alcohol from the lithium chloride solution, concentrating the rectified mother solution, and performing spray drying to obtain anhydrous lithium chloride particles. The method adopts a nanofiltration membrane clean separation and elution crystallization combined process to carry out magnesium sulfate interception and purification on the magnesium sulfate subtype salt lake brine for the first time, realizes high-efficiency production of lithium chloride, is a new process for extracting lithium from the magnesium sulfate subtype salt lake, can reduce material consumption and energy consumption, can repeatedly recycle the adopted low-carbon alcohol, has no three-waste pollution, and is easy for industrial implementation.
Description
Technical Field
The invention relates to a process for extracting lithium from a salt lake, in particular to a process for directly preparing lithium chloride from magnesium sulfate subtype salt lake brine.
Background
Lithium plays an important role in the new energy industry as a national strategic reserve resource. The lithium resource reserve occupies an important position in the total lithium resource of the world in China, wherein the lithium resource of salt lake brine accounts for more than 92 percent, magnesium sulfate subtype salt lakes are abundant, and the lithium resource is mostly distributed in thousands of large and small salt lakes such as Qinghai, Tibet, Xinjiang and the like. Lithium chloride is an important lithium salt product, and has a very important application in the production of lithium metal, in addition to being used in air conditioner dehumidifiers, bleaching powders, pesticides, synthetic fibers, pharmaceutical industry, lithium batteries, metal alloy welding agents or cosolvents. At present, the lithium extraction method for domestic industrialization mainly comprises an ion exchange membrane method, a calcination leaching method, an adsorption method, a solar pond technology, a combined brine-adding method and the like, and industrial production devices are established and part of the devices are put into production. Throughout the domestic research on the technology for extracting lithium from salt lakes, due to the poor grade of the lithium-containing salt lakes in China, the key and key technologies are around extracting lithium from the salt lakes with high magnesium-lithium ratio, most of the technology adopts salt fields to naturally tedge and crystallize to obtain lithium-rich old brine, then the magnesium-lithium ratio is reduced by a magnesium precipitation and impurity removal mode, and finally carbonate precipitates to obtain a lithium carbonate product.
CN1872688A discloses a preparation method of anhydrous lithium chloride, which is to add calcium chloride into a lithium sulfate solution to obtain a lithium chloride solution, and then remove impurities, concentrate under reduced pressure, cool and crystallize in sequence to obtain the anhydrous lithium chloride, wherein the method has harsh requirements on raw materials, and the medicament consumption in the impurity removal process is too large, which does not meet the process requirements of environmental protection; CN101172624A discloses a preparation method of high-purity anhydrous lithium chloride, which is characterized in that high-potassium-sodium lithium chloride-containing brine is used as a raw material, impurities are sequentially removed to obtain refined mother liquor, potassium chloride and sodium chloride are removed through evaporation and filtration, high-lithium mixed salt is obtained through spray drying, and a low-carbon organic solvent is added to extract lithium chloride; CN106629788A discloses a process for producing lithium chloride, which is characterized in that brine desorption liquid prepared in the lithium extraction process by an ion exchange adsorption method is used as a raw material, the lithium liquid is concentrated by a reverse osmosis method and an electrodialysis method, and then the anhydrous lithium chloride is obtained by repeated purification, dehydration and drying by adsorption resin and the like. At present, there are few reports or researches on direct nanofiltration of magnesium sulfate and lithium chloride by using magnesium sulfate subtype salt lake brine to intercept magnesium sulfate so as to realize magnesium and lithium separation and prepare lithium chloride at home and abroad.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects in the prior art, and provide a process for preparing lithium chloride from magnesium sulfate subtype salt lake brine, which has the advantages of simple process, low energy consumption, low material consumption and low production cost, can effectively realize magnesium sulfate interception and physical separation, and has high purity of the obtained lithium chloride.
The technical scheme adopted by the invention for solving the technical problems is as follows: a process for preparing lithium chloride from magnesium sulfate subtype salt lake brine comprises the following steps:
(1) freezing nitre: freezing nitre in magnesium sulfate subtype salt lake brine at the low temperature of-20-0 ℃ until SO4 2-/Mg2+The mass ratio is 2-5, so that purified raw water is obtained;
wherein the salinity of the raw material magnesium sulfate subtype salt lake brine is 80-150 g/L, and SO4 2-/Mg2+The mass ratio is 6-10;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1) to obtain lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 65-80%;
(3) evaporation and crystallization: evaporating moisture which is equivalent to 85-95% of the mass of the lithium-rich water produced in the step (2) to a common saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain a high-concentration lithium-containing mother solution;
(4) elution and crystallization: adding low-carbon alcohol which is 1-3 times of the high-concentration lithium-containing mother liquor in mass into the high-concentration lithium-containing mother liquor obtained in the step (3), carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride solution;
(5) spray drying: and (4) recovering low-carbon alcohol from the lithium chloride feed liquid obtained in the step (4) through a rectifying tower process, further concentrating the rectifying mother liquid until the mass concentration of lithium chloride is 40-50%, and then performing spray drying to obtain anhydrous lithium chloride particles.
The diameter of the anhydrous lithium chloride particles obtained by the method is 1-6 mu m (more than 80%), and the purity is more than or equal to 99.0%.
The percentages stated in the present invention are, unless otherwise stated, percentages by mass.
In the step (1), the low-temperature nitrate freezing is used for freezing and crystallizing to separate out mirabilite solid, reduce the mineralization degree of brine and improve the membrane flux and the chemical performance thereof; meanwhile, the concentration of sulfate radicals is reduced, the enrichment and scaling of calcium sulfate in the nanofiltration separation process can be avoided, and the membrane pollution and the like are reduced; the frozen nitre brine SO4 2-/Mg2+The mass ratio range can obtain better freezing denitration effect, and is more beneficial to the interception of magnesium sulfate and the separation of magnesium and lithium at the later stage.
Further, in the step (2), a nanofiltration membrane is adopted for nanofiltration separation, and the nanofiltration membrane is MgSO4The organic polymer roll-up membrane with the rejection rate of 90-98%, the LiCl transmittance is not less than 85%, the operation pressure is 3.0-4.5 MPa, and the operation temperature is 15-40 ℃. Wherein, researchers find out that the salt is in the range of the salinity of the brine and SO through a large amount of nano-filtration experimental researches4 2-/Mg2+2-5, the rejection rate of the nanofiltration membrane to divalent ions is higher and reaches more than 90%, and the nanofiltration membrane has a preferential rejection rule for sulfate radicals, namely SO4 2-The existence of the metal ions is more beneficial to the interception of the nanofiltration membrane, so that the charge negativity of the surface of the nanofiltration membrane is changed and Mg is induced2+The magnesium sulfate is intercepted, so that the high-efficiency interception of the magnesium sulfate is realized, the magnesium-lithium ratio of brine is greatly reduced, and a brine system and a subsequent evaporative crystallization process are simplified; under the conditions of temperature and pressure, the nanofiltration membrane has ideal divalent ion rejection rate and water production flux.
Further, in the step (2), the mass ratio of the lithium-rich produced water to the purified raw water is controlled to avoid that the mineralization of brine is continuously increased due to continuous concentration of concentrated water in the nanofiltration process, so that the osmotic pressure of the brine and the nanofiltration power consumption are increased, and the magnesium sulfate interception effect is influenced.
Further, in the step (3), the evaporation concentration method can be natural evaporation, multiple-effect evaporation or novel MVR evaporation; researchers find through a large amount of evaporation test researches that the precipitation amount of sodium chloride and potassium chloride is large, the entrainment amount of mother liquor is small, the lithium loss is small, and the recovery of the mother liquor and lithium salt is further reduced within 85% -95% of the evaporation water loss.
In the step (4), the lower alcohol is at least one of lower organic alcohols having less than 6 carbon atoms, and more preferably at least one of anhydrous methanol, anhydrous ethanol, n-propanol, isopropanol and the like. Researches show that in the mass ratio of the high-concentration lithium-containing mother liquor to the low-carbon alcohol organic reagent of 1 (1-3), only lithium chloride is soluble, the elution crystallization rate of other impurity salts such as potassium salt, sodium salt, sulfate and magnesium salt is high, the impurity removal efficiency is high, and the actual consumption is low.
In the step (5), researchers find through a large number of experimental studies that the spray drying effect is optimal within the range of 40% -50% of the mass concentration of lithium chloride, and the obtained anhydrous lithium chloride particles are good in whiteness, granularity and uniformity.
The invention adopts the combined process of nanofiltration membrane clean separation and solvent-out crystallization to carry out magnesium sulfate interception and purification on magnesium sulfate subtype salt lake brine for the first time, realizes high-efficiency production of lithium chloride, is a new process for extracting lithium from the magnesium sulfate subtype salt lake, can reduce material consumption and energy consumption, can repeatedly recycle low-carbon alcohol, has no three-waste pollution, is easy to industrially implement, and is a new process for directly preparing lithium chloride from the magnesium sulfate subtype salt lake brine with industrial development prospect.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
The embodiment adopts brine as brine of a magnesium sulfate subtype salt lake in a certain plateau of the Tibetan of China, the mineralization degree is 95g/L, and the main mineral elements comprise the following chemical components: SO (SO)4 2-:3.8wt%，Mg2+：0.5wt%，Li+:0.08wt%，SO4 2-/Mg2+Mass ratio: 7.6, Mg/Li mass ratio: 6.25.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of 0 ℃ until SO4 2-/Mg2+The mass ratio is 2.4, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 3.0MPa, the operating temperature is 15 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 80%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The LiCl transmittance of the organic polymer roll-type membrane with the rejection rate of 98 percent is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 85 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 2.5 weight percent;
(4) elution and crystallization: adding methanol which is 2 times of the mass of the high-concentration lithium-containing mother liquor obtained in the step (3) into the high-concentration lithium-containing mother liquor, carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride feed liquid;
(5) spray drying: and (3) recovering methanol from the lithium chloride solution obtained in the step (4) through a rectifying tower process at 70 ℃, further concentrating the rectifying mother liquor until the mass concentration of lithium chloride is 42%, and performing spray drying to obtain anhydrous lithium chloride particles with the particle diameter of 1-6 microns (80%) and the purity of 99.5%.
Example 2
The embodiment adopts bittern which is 120g/L of mineralization degree of magnesium sulfate subtype salt lake bittern in certain plateau of Tibet of China, and the main mineral elements of the bittern comprise the following chemical components: SO (SO)4 2-:5.5wt%，Mg2+：0.6wt%，Li+:0.1wt%，SO4 2-/Mg2+Mass ratio: 9.2, Mg/Li mass ratio: 6.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of-10 ℃ until SO4 2-/Mg2+The mass ratio is 4.5, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 4.3MPa, the operating temperature is 40 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 65%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The interception rate of the organic polymer roll-type membrane is 90 percent, and the LiCl transmittance is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 90 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 4.5 percent;
(4) elution and crystallization: adding ethanol with the mass being 3 times that of the high-concentration lithium-containing mother liquor into the high-concentration lithium-containing mother liquor obtained in the step (3), carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride solution;
(5) spray drying: and (3) recovering ethanol from the lithium chloride feed liquid obtained in the step (4) through a rectifying tower process at 85 ℃, further concentrating the rectified mother liquid until the mass concentration of lithium chloride is 50%, and performing spray drying to obtain anhydrous lithium chloride particles with the particle diameter of 1-6 microns (85%) and the purity of 99.3%.
Example 3
In the embodiment, the adopted brine is the brine of a plateau magnesium sulfate subtype salt lake abroad, the mineralization degree is 140g/L, and the main mineral elements comprise the following chemical components: SO (SO)4 2-:2.65wt%，Mg2+：0.43wt%，Li+:0.05wt%，SO4 2-/Mg2+Mass ratio: 6.16, Mg/Li mass ratio: 8.6.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of-15 ℃ until SO4 2-/Mg2+The mass ratio is 3.2, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 4.0MPa, the operating temperature is 35 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 70%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The LiCl transmittance of the organic polymer roll-type membrane with the rejection rate of 95 percent is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 95 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 4.8 percent;
(4) elution and crystallization: adding n-propanol with the mass 1 time that of the high-concentration lithium-containing mother liquor obtained in the step (3) into the high-concentration lithium-containing mother liquor, carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride solution;
(5) spray drying: and (3) recovering n-propanol from the lithium chloride feed liquid obtained in the step (4) through a rectifying tower process at 100 ℃, further concentrating the rectifying mother liquid until the mass concentration of lithium chloride is 48%, and performing spray drying to obtain anhydrous lithium chloride particles with the particle diameter of 1-6 microns (82%) and the purity of 99.4%.
Example 4
In the embodiment, the adopted brine is the brine of a plateau magnesium sulfate subtype salt lake abroad, the mineralization degree is 115g/L, and the main mineral elements comprise the following chemical components: k+：0.32wt%，SO4 2-:6.5wt%，Mg2+：0.78wt%，Li+:0.06wt%，SO4 2-/Mg2+Mass ratio: 8.33, Mg/Li mass ratio: 13.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of 18 ℃ below zero to SO4 2-/Mg2+The mass ratio is 2.1, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 3.2MPa, the operating temperature is 26 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 75%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The LiCl transmittance of the organic polymer roll-type membrane with the rejection rate of 95 percent is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 88 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 4.3 wt%;
(4) elution and crystallization: adding the high-concentration lithium-containing mother liquor obtained in the step (3) into methanol and ethanol mixed organic reagents which are obtained by recovering the high-concentration lithium-containing mother liquor in the embodiment 1 and the embodiment 2 and have the mass which is 2.5 times that of the high-concentration lithium-containing mother liquor, carrying out elution crystallization, and carrying out solid-liquid separation to obtain lithium chloride feed liquid;
(5) spray drying: and (3) recovering methanol and ethanol from the lithium chloride feed liquid obtained in the step (4) through a rectifying tower process at the temperature of 90 ℃, further concentrating the rectifying mother liquid until the mass concentration of lithium chloride is 45%, and performing spray drying to obtain anhydrous lithium chloride particles with the particle diameter of 1-6 microns (83%) and the purity of 99.4%.
Example 5
The embodiment adopts brine as brine of a magnesium sulfate subtype salt lake in a certain plateau of the Tibetan of China, the mineralization degree is 95g/L, and the main mineral elements comprise the following chemical components: SO (SO)4 2-:3.8wt%，Mg2+：0.5wt%，Li+:0.08wt%，SO4 2-/Mg2+Mass ratio: 7.6, Mg/Li mass ratio: 6.25.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of 0 ℃ until SO4 2-/Mg2+The mass ratio is 2.4, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 3.0MPa, the operating temperature is 15 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 80%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The LiCl transmittance of the organic polymer roll-type membrane with the rejection rate of 98 percent is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 85 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 2.5 weight percent;
(4) elution and crystallization: adding n-butyl alcohol with the mass 2 times that of the high-concentration lithium-containing mother liquor into the high-concentration lithium-containing mother liquor obtained in the step (3), carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride feed liquid;
(5) spray drying: and (3) recovering n-butanol from the lithium chloride solution obtained in the step (4) through a rectifying tower process at 120 ℃, further concentrating the rectifying mother liquor until the mass concentration of lithium chloride is 42%, and performing spray drying to obtain anhydrous lithium chloride particles with particle diameter of 1-6 microns (80.5%) and purity of 99.1%.
Example 6
In the embodiment, brine is adopted to treat a certain height in Tibet of ChinaThe mineralization degree of the original magnesium sulfate subtype salt lake brine is 120g/L, and the main mineral elements of the original magnesium sulfate subtype salt lake brine comprise the following chemical components: SO (SO)4 2-:5.5wt%，Mg2+：0.6wt%，Li+:0.1wt%，SO4 2-/Mg2+Mass ratio: 9.2, Mg/Li mass ratio: 6.
(1) freezing nitre: freezing the magnesium sulfate subtype salt lake brine at the low temperature of-10 ℃ until SO4 2-/Mg2+The mass ratio is 4.5, and purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1), wherein the operating pressure is 4.3MPa, the operating temperature is 40 ℃, obtaining lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 65%;
the nanofiltration separation adopts a nanofiltration membrane which is MgSO4The interception rate of the organic polymer roll-type membrane is 90 percent, and the LiCl transmittance is more than or equal to 85 percent;
(3) evaporation and crystallization: evaporating water which is equivalent to 90 percent of the mass of the lithium-rich water produced in the step (2) to a saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain high-concentration lithium-containing mother liquor, wherein the concentration of lithium ions reaches 4.5 percent;
(4) elution and crystallization: adding n-amyl alcohol with the mass being 3 times that of the high-concentration lithium-containing mother liquor obtained in the step (3) into the high-concentration lithium-containing mother liquor, carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride solution;
(5) spray drying: and (3) recovering n-amyl alcohol from the lithium chloride solution obtained in the step (4) through a rectifying tower process at the temperature of 140 ℃, further concentrating the rectifying mother liquor until the mass concentration of lithium chloride is 50%, and performing spray drying to obtain anhydrous lithium chloride particles with the particle diameter of 1-6 microns (81%) and the purity of 99.0%.
Claims (5)
1. A process for preparing lithium chloride from magnesium sulfate subtype salt lake brine is characterized by comprising the following steps:
(1) freezing nitre: freezing nitre in magnesium sulfate subtype salt lake brine at the low temperature of-20-0 ℃ until SO4 2-/Mg2+The mass ratio is 2-5, so that purified raw water is obtained;
(2) and (4) nanofiltration: carrying out nanofiltration separation on the purified raw water obtained in the step (1) to obtain lithium-rich produced water and nanofiltration concentrated water, and controlling the mass ratio of the lithium-rich produced water to the purified raw water to be 65-80%;
(3) evaporation and crystallization: evaporating moisture which is equivalent to 85-95% of the mass of the lithium-rich water produced in the step (2) to a common saturation point, and precipitating a large amount of sodium chloride and potassium chloride to obtain a high-concentration lithium-containing mother solution;
(4) elution and crystallization: adding low-carbon alcohol which is 1-3 times of the high-concentration lithium-containing mother liquor in mass into the high-concentration lithium-containing mother liquor obtained in the step (3), carrying out elution crystallization, and carrying out solid-liquid separation to obtain a lithium chloride solution;
(5) spray drying: recovering low-carbon alcohol from the lithium chloride feed liquid obtained in the step (4) through a rectifying tower process, further concentrating the rectifying mother liquid until the mass concentration of lithium chloride is 40-50%, and then performing spray drying to obtain anhydrous lithium chloride particles;
in the step (1), the salinity of the raw material magnesium sulfate subtype salt lake brine is 80-150 g/L, and SO4 2-/Mg2+The mass ratio is 6-10;
in the step (4), the lower alcohol is at least one of lower organic alcohols with the carbon number less than 6.
2. The process for preparing lithium chloride from magnesium sulfate subtype salt lake brine as claimed in claim 1, wherein in the step (2), the nanofiltration separation is performed by using a nanofiltration membrane which is MgSO4The retention rate of the organic polymer roll-up membrane is 90-98%.
3. The process for preparing lithium chloride from magnesium sulfate subtype salt lake brine according to claim 2, wherein the transmittance of a nanofiltration membrane LiCl is not less than 85%, the operation pressure is 3.0-4.5 MPa, and the operation temperature is 15-40 ℃.
4. The process for preparing lithium chloride from the magnesium sulfate subtype salt lake brine as claimed in claim 1 or 2, wherein in the step (3), the evaporation concentration method is natural evaporation, multi-effect evaporation or a novel MVR evaporation method.
5. The process for preparing lithium chloride from the magnesium sulfate subtype salt lake brine as claimed in claim 1 or 2, wherein the lower alcohol is at least one of absolute methanol, absolute ethanol, n-propanol and isopropanol.
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| CN112919506B (en) * | 2021-03-03 | 2022-07-26 | 中国恩菲工程技术有限公司 | Device and method for continuously producing lithium chloride from salt lake lithium-rich brine |
| CN116623002B (en) * | 2023-05-04 | 2024-02-23 | 西部矿业股份有限公司 | Method for removing magnesium ions in zinc hydrometallurgy based on solution crystallization method |
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